we'll also show you the moment that threatened to steal the show from the president when former arizona congresswoman, gabby giffords, 20 months after she was shot in the head, led the audience in the pledge of allegiance. that clip in its entirety later. but we begin with president obama and closing argument. 20,000 supporters packing into the convention hall. the president accepted his party's nomination for a second term. after a warm krupp from vice president biden, he offered a defense to his policies, saying he now needs more time to build on the progress he's made. >> if you reject the notion that this nation's promise is reserved for the few, your voice must be heard in this election. if you reject the notion that our government is forever beholden to the highest bidder, you need to stand up in this election. if you believe in a country where everyone gets a fair shot and everyone does their fair share and everyone plays by the same rules, then i need you to vote this november. >> borrowing a quote from abraham lincoln, president obama acknowledges the challenges of his own pres